Reflex harmonic generator



June 10, 1947. J, w. TILEY REFLEX amuouxc GENERATOR INVENTOR.

Filed Aug. 31, 1944 MODULATOR Patented June 10, 1947 REFLEX HARMONIC GENERATOR John W. Tlley, Philadelphia, Pa., assignmto Philco Corporation, Philadelphia, Pa., a corporation of Pennsylvania Application August 31, 1944, Serial No. 552,139

9 Claims.

The present invention relates to the multiplication of frequencies in the ultra-high frequency range, and more particularly such multiplication with an ultra-high frequency tube having a single resonant cavity.

Heretofore velocity modulated electron beam tubes having a plurality of resonant cavities associated therewith have been used for the multiplication of frequencies in the ultra-high frequency range. Certain ultra-high frequency tubes are available which have only a single resonant cavity and it would be desirable to pro vide harmonic operation with a simplified circuit and tube of this type.

In accordance with the present invention a velocity modulated electron beam tube, such as the Klystron type 417 is used for frequency multiplication. A radio frequency signal is applied between the control grid and another point on the tube, such as the cathode or an external band located in the proximity of the cathode. The radio frequency is applied to the grid through a tuned resonant transmission line and means are provided to-prevent the grid from blocking. The resonant cavity of the vacuum tube is tuned to a high harmonic of the frequency applied to the grid. With the repeller electrode at the same potential as the resonant cavity a small harmonic output is obtained. To increase the harmonic output the repeller electrode is supplied with a potential smaller than that supplied to the resonant cavity so as to introduce a certain amount of feed-back into the circuit.

It therefore is an object of the present invention to provide a new and improved circuit and apparatus for frequency multiplication in the ultra-high frequency range.

It is another object of the present invention to provide an improved ultra-high frequency multiplier utilizing a velocity modulation tube having a single resonant cavity.

Other and further objects of the present invention subsequently will become apparent by reference to the following description taken in connection with the accompanying drawing, wherein Figure 1 schematically and diagrammatically shows a velocity modulation tube and circuit for frequency multiplication in accordance with the present invention, and Figures 2 and 3 show modifications.

In Figure 1 there has been diagrammatically represented a velocity modulation tube which is exemplified by a Klystron type 417 tube having a glass envelope ii containing a cathode heater i2, a heated cathode i3, 9. control grid II, a

repeller electrode l5 and a pair of grids it which are connected to the externally arranged resonant cavity ii. To illustrate an alternative manner of operating the vacuum tube there has been an external band I8 positioned generally in the proximity of the cathode structure of the vacuum tube.

A suitable source of high frequency, which may be within the range from to 500 megacycles, is indicated by source I! which, through a tuned resonant transmission line represented by the conductors 2| and 22 and the tuning capacitor 29, supplies energy to the grid It and to either the cathode i3 or the external coupling band i9. A switch 24 has been shown so that connection may be made either to the cathode [3 or the external band i8. In order to prevent grid blocking, a resistor 25 is connected between the grid and cathode which, in the case of a type 417 Klystron tube, may have a value of 30,000 ohms. The high frequency source l9 supplies a signal having a maximum radio frequency voltage of from 30 to 35 volts.

The conductors to the heater I2 may be provided with suitable choke inductors 26 and 21. A choke inductor 28 may be connected between the cathode II, as is customary, and the negative terminal of a source of potential 28. The source of potential 29, for a tube of the type mentioned, has a value on the order of 500 volts, and the positive terminal thereof is grounded. The full voltage of the source 29 is applied to the resonant cavity I]. A voltage divider 9| is connected across the source 29 and the adjustable contact 32 is connected to the repeller electrode It.

The mode ofoperation of the circuit arrangement above described will become apparent by assuming that the generator i9 is operating at 200 megacycles and is supplying a potential of 35 volts to the grid. The resonant cavity voltage is 500 volts with respect to the cathode and the cavity is tuned to a high harmonic of the generator i9, as for example the fifteenth harmonic. With the adjustable contact 32 of the voltage divided 3| at the positive end, the repeller electrode l5 will have applied thereto a potential of 500 volts with respect to the cathode. With the repeller electrode l5 at this potential, a small amount of radio frequency energy, 3,000 megacycles, is obtained at the output of the cavity I1 which, as is customary, may be obtained by a probe and coaxial conductor arrangement. If new the adjustable contact 32 on the voltage divider Si is moved so as to reduce the potential on the repeller electrode ll, feed-back will be introduced into the circuit to increase the output so as to cause the tube to operate or function as a frequency ltiplier. It has been noted that if the potential on the repeller electrode I! is so reduced as to be at a negative point with respect to the cathode li, oscillations may be produced without the benefit of radio frequency excitation from the source II, but such operation is deemed not desirable for the purpose of frequency multiplication. The deviation in frequency is limited by the Q of the resonant cavity H which may be controlled by resistive loading.

In addition to operation of the type described, frequency modulation of the output resonant cavity may be obtained, as shown in Fig. 2, by frequency modulating the source is by means of a modulator 33 connected to the source i9. As an alternative, the modulator may be connected directly to the transmission line conductors 2| and 22 so as to supply the modulation directly to the grid of the vacuum tube. as shown in Fig. 3. This mode of frequency modulation has the advantage of tending to eliminate frequency shift due to temperature or other changes in the velocity modulation tube, thus making it possible to use this arrangement where a high degree of control of frequency is desired.

Preferably the voltages supplied to the velocity modulation tube are so adjusted that no oscillation takes place unless a. radio frequency voltage is impressed upon the input grid Id. The grid ll may be at a radio frequency potential with respect to the cathode II or with respect to the external band I8 which may be installed on the neck of the tube, or the grid may be at a radio frequency potential with respect to the cavity i'l. By means of the present invention frequency multiplication maybe obtained without the necessity of special types of tubes.

While for the purpose of illustrating and describing the present invention a certain embodiment has been shown, it is to be understood that the invention is not to be limited thereby, since such variations in the circuit arrangements and in the instrumentalitles employed are contemplated as are commensurate with the spirit and scope of the invention defined in the appended claims.

This invention is hereby claimed as follows:

1. A velocity modulation electron beam vacuum tube having a cathode, a control grid, a repeller electrode and a plurality of grids connected to a cavity resonator, a. source of potential connected between said cathode and said resonator, a source of potential of lower value connected between said cathode and said repeller electrode, a source of high frequency energ connected to said grid, said source of high frequency ener y being a sub-multip e of the resonant frequency of said resonator.

2. A velocity modulation vacuum tube having a cathode. a control grid, a repeller electrode, and a plurality of grids connected to a cavity resonator, a source of potential connected to said resonator and said repeller electrode, means connected with said source for adjusting the potential of the repeller electrode to a value less than that applied to said resonator, and a source of high frequency energy connected between said grid and another point of said vacuum tube, said resonator being tuned to a high harmonic of the frequency supplied by said source of high frequency energy.

3. The method of generating harmonics with a velocity modulation vacuum tube having a cathode, a control grid, 9. repeller electrode, and a cavity resonator. comprising applying a direct current potential between said cathode and said resonator, applying a direct current potential of lesser value between said cathode and said repeller electrode, and applying to said cathode high frequency energy which is a sub-multiple of the resonant frequency of said resonator.

4. The method of generating harmonics with a velocity modulation vacuum tube having a cathode, a control grid, a repeller electrode, and a plurality of grids connected to a cavity resonator. comprising applying a certain direct current potential between said cathode and said resonator, app ying a direct current potential of lesser value than said certain direct current potential between said cathode and said repeller electrode, applying between said grid and said cathode high frequency energy, and adjusting said resonator to a frequency which is a higher harmonic of the high frequency energy applied to said grid.

5. A method of generating harmonics with a velocity modulation vacuum tube having a control grid, a repeller electrode, and a cavity resonator, comprising applying a direct current potential between the cathode of said tube and said resonator, applying a direct current potential of lesser value to said repeller electrode, applying between said grid and another electrode of said vacuum tube high frequency energy, and adjusting said resonator to a frequency which is a higher harmonic of the energy applied to said grid.

6. The method of operating a. velocity modulation vacuum tube having a cathode, a control grid, a repeller electrode, a cavity resonator, and a plurality of grids connected to said resonator comprising applying a certain potential between said cathode and said resonator, applying a lesser potential between said cathode and said repeller electrode, applying high radio frequency energy to the grid, adjusting said resonator to a frequency which is a higher harmonic of the energy applied to said grid, and modulating the energy applied to said grid.

7. A velocity modulation electron beam vacuum tube having a cathode, a control grid, a repellerelectrode, a cavity resonator, and a plurality of grids connected to said resonator, a source of potential, means connecting said source between said cathode and said resonator, means connecting said repeller-electrode to an intermediate point of said source, and a source of frequency modulated high frequency energy connected to said grid, said resonator being tuned to a high harmonic of said source of said high frequency energy.

8. A velocity modulation vacuum tube having a cathode. a control grid, a repeller-electrode, a

cavity resonator, and a plurality of grids connected to said resonator, a source of direct current potential connected between said cathode and said resonator, means connected from said source to said repeller-electrode for supplying a reduced potential to said repeller-electrode, a source of high frequency energy connected between said grid and said cathode, and a signal source connected between said grid and said cathode to frequency modulate the output energy of said vacuum tube, said resonator being tuned to a higher harmonic of the high frequency energy supplied to said grid.

9. A velocity modulation vacuum tube having a cathode, a, control grid, a repeller-electrode, and a cavity resonator, means connected between said cathode and said resonator for applying a positive potential to said resonator relative to said oath-- quency modulate the energy appearing in said resonator.

JOHN W. 'I'ILEY.

REFERENCES CITED repeller-electrode a potential of a native value p "have to 1d mnator, a of high The iollowing references are of record in the adobe! radio energy connected between said grid me this patent and another point adjacent said tube. said reson- UNITED STATES PATENTS ator being tuned to a relatively high harmonic oi. m Number Name Date the radio energy supplied to sald arid. a source oi 2,245.82, val-1m June 17, 1941 modulation, and means connecting said modula- 2 359 59 Hansen 1; a] o 2 19 tion source to the grid of said vacuum tube to he 3,250,511 v -1 t 3,1 July 29, 194

Disclaimer 2,422,146.-John W. Tiley, Philadelphia, Pa. Rnrmzx HAnuomc GENERATOR. Patent dated June 10, 1947. Disclaimer filed Jan. 9, 1948, by the assignee,

Philco Corporation.

Hereby disclaims from the scope of all apparatus or method .wherein the velocity modulation tube is caused to be sel oscillatory b virtue of the unidirectional tentials applied thereto, said claims being here y to an apparatus or me od wherein the unidirectional potentials applied to the velocity modulation tube are such that the tube is not self-oscillatory but is caused to oscillate by the high frequency energy applied to the input electrodes of the tube.

of the claims of the said Letters Patent an [Oficicl Gazette February 10 1948.]

cathode and said resonator for applying a positive potential to said resonator relative to said oath-- quency modulate the energy appearing in said resonator.

JOHN W. 'I'ILEY.

REFERENCES CITED repeller-electrode a potential of a native value p "have to 1d mnator, a of high The iollowing references are of record in the adobe! radio energy connected between said grid me this patent and another point adjacent said tube. said reson- UNITED STATES PATENTS ator being tuned to a relatively high harmonic oi. m Number Name Date the radio energy supplied to sald arid. a source oi 2,245.82, val-1m June 17, 1941 modulation, and means connecting said modula- 2 359 59 Hansen 1; a] o 2 19 tion source to the grid of said vacuum tube to he 3,250,511 v -1 t 3,1 July 29, 194

Disclaimer 2,422,146.-John W. Tiley, Philadelphia, Pa. Rnrmzx HAnuomc GENERATOR. Patent dated June 10, 1947. Disclaimer filed Jan. 9, 1948, by the assignee,

Philco Corporation.

Hereby disclaims from the scope of all apparatus or method .wherein the velocity modulation tube is caused to be sel oscillatory b virtue of the unidirectional tentials applied thereto, said claims being here y to an apparatus or me od wherein the unidirectional potentials applied to the velocity modulation tube are such that the tube is not self-oscillatory but is caused to oscillate by the high frequency energy applied to the input electrodes of the tube.

of the claims of the said Letters Patent an [Oficicl Gazette February 10 1948.]

Certificate of Correction Potent N0. 2,422,146. June 10, 1947.

' JOHN W. TILEY It is hereby certified that error appears in the above numbered petent requiring correction as follows: In the drawing, the present sheet should heeeneeled end, the

sheet as shown: below, containing Figures 1, 2, and 3-, should be substituted therefor.

as part of the Letters PetenfP- JunelO, 1947- J. w.-s'm..e-r-

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Signed end sealed this 8rd day of Februery, A. D. 1948.

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